NHibernate MappingException: Could not compile the mapping document

Question

On my dev web app NHibernate is working just dandy. When I precompile and deploy the site, I get a MappingException when the SessionFactory is created.

Here's some info from the trace:

NHibernate.Cfg.Environment 2010-07-15 09:20:59,577 [7] INFO NHibernate.Cfg.Environment [(null)] - NHibernate 2.1.2.4000 (2.1.2.4000) 0.452436832055471 0.232383 NHibernate.Cfg.Environment 2010-07-15 09:20:59,718 [7] INFO NHibernate.Cfg.Environment [(null)] - Bytecode provider name : lcg 0.522780409241957 0.070344 NHibernate.Cfg.Environment 2010-07-15 09:20:59,734 [7] INFO NHibernate.Cfg.Environment [(null)] - Using reflection optimizer 0.529107470362853 0.006327 NHibernate.Cfg.Configuration 2010-07-15 09:20:59,827 [7] INFO NHibernate.Cfg.Configuration [(null)] - Mapping resource: Kctc.BusinessLayer.Mappings.StoredWill.hbm.xml 0.623336485503046 0.094229 NHibernate.Dialect.Dialect 2010-07-15 09:21:00,109 [7] INFO NHibernate.Dialect.Dialect [(null)] - Using dialect: NHibernate.Dialect.MsSql2008Dialect 0.91570185596214 0.292365 NHibernate.Cfg.Configuration 2010-07-15 09:21:01,390 [7] ERROR NHibernate.Cfg.Configuration [(null)] - Could not compile the mapping document: Kctc.BusinessLayer.Mappings.StoredWill.hbm.xml NHibernate.MappingException: Could not compile the mapping document: Kctc.BusinessLayer.Mappings.StoredWill.hbm.xml ---> System.InvalidOperationException: Unable to generate a temporary class (result=1). error CS2001: Source file 'C:\WINDOWS\TEMP\shp2uoc8.0.cs' could not be found error CS2008: No inputs specified

at System.Xml.Serialization.Compiler.Compile(Assembly parent, String ns, XmlSerializerCompilerParameters xmlParameters, Evidence evidence) at System.Xml.Serialization.TempAssembly.GenerateAssembly(XmlMapping[] xmlMappings, Type[] types, String defaultNamespace, Evidence evidence, XmlSerializerCompilerParameters parameters, Assembly assembly, Hashtable assemblies) at System.Xml.Serialization.TempAssembly..ctor(XmlMapping[] xmlMappings, Type[] types, String defaultNamespace, String location, Evidence evidence) at System.Xml.Serialization.XmlSerializer.GenerateTempAssembly(XmlMapping xmlMapping, Type type, String defaultNamespace) at System.Xml.Serialization.XmlSerializer..ctor(Type type, String defaultNamespace) at System.Xml.Serialization.XmlSerializer..ctor(Type type) at NHibernate.Cfg.XmlHbmBinding.Binder.Deserialize[T](XmlNode node) at NHibernate.Cfg.XmlHbmBinding.MappingRootBinder.Bind(XmlNode node) at NHibernate.Cfg.Configuration.AddValidatedDocument(NamedXmlDocument doc) --- End of inner exception stack trace --- 2.20609881982207 1.290397 Unhandled Execution Error Could not compile the mapping document: Kctc.BusinessLayer.Mappings.StoredWill.hbm.xml at NHibernate.Cfg.Configuration.LogAndThrow(Exception exception) at NHibernate.Cfg.Configuration.AddValidatedDocument(NamedXmlDocument doc) at NHibernate.Cfg.Configuration.ProcessMappingsQueue() at NHibernate.Cfg.Configuration.AddDocumentThroughQueue(NamedXmlDocument document) at NHibernate.Cfg.Configuration.AddXmlReader(XmlReader hbmReader, String name) at NHibernate.Cfg.Configuration.AddInputStream(Stream xmlInputStream, String name) at NHibernate.Cfg.Configuration.AddResource(String path, Assembly assembly) at NHibernate.Cfg.Configuration.AddAssembly(Assembly assembly) at Kctc.BusinessLayer.NHibernateSessionFactory.get_SessionFactory() in C:\Kctc\Trunk\Kctc.BusinessLayer\NHibernateSessionFactory.cs:line 26
at Kctc.BusinessLayer.NHibernateSessionFactory.OpenSession() in C:\Kctc\Trunk\Kctc.BusinessLayer\NHibernateSessionFactory.cs:line 39
at Developers_Test.ListSquirps(Object sender, EventArgs e) at System.Web.UI.WebControls.Button.OnClick(EventArgs e) at System.Web.UI.WebControls.Button.RaisePostBackEvent(String eventArgument) at System.Web.UI.WebControls.Button.System.Web.UI.IPostBackEventHandler.RaisePostBackEvent(String eventArgument) at System.Web.UI.Page.RaisePostBackEvent(IPostBackEventHandler sourceControl, String eventArgument) at System.Web.UI.Page.RaisePostBackEvent(NameValueCollection postData)
at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) 2.20665643259129 0.000558

This suggests to me either that the mapping file has an error or could not be found. But if the dev app works fine, how can there be an issue with the mapping file when it is precompiled and deployed?!

Does anyone have any suggestion as to what might be happening here?

Thanks

Answer 1

Okay, I've got it. The XmlSerializer class which is invoked during the creation of the SessionFactory needs write access to (by default) C:\Windows\TEMP so that it can generate some stuff and whack it in there.

Alternatively, you can follow the hack on this blog http://www.hanselman.com/blog/ChangingWhereXmlSerializerOutputsTemporaryAssemblies.aspx. This changes the default location that XmlSerializer stores its shiznit. All you have to do is add the following element within the configuration element of your web.config / app.config file:

<system.xml.serialization>
  <xmlSerializer tempFilesLocation="C:\SomeFolder\SomeOtherFolder\WhereeverYouWant"/>
</system.xml.serialization>

The first solution feels like a security issue, and the second one feels like a clumsy hack with hard-to-foresee consequences.

Why is this so poorly documented?

Answer 2

Check that the .hbm.xml file is defined as an embedded resource in your project.